FIG. 1 is a schematic view showing a monitoring apparatus and its peripheral arrangement in a conventional electric power system. In the conventional electric power system, a plurality of devices #1 to #n transmit data to a monitoring apparatus 10, and the monitoring apparatus 10a saves the data in an electric power system DB 12 via a dedicated bus 11.
A processor (not shown) in the monitoring apparatus 10a functions as a plurality of internal application units 13A to 13C by executing a plurality of internal application programs A to C (to be referred to as internal applications A to C hereinafter) in a memory (not shown). The plurality of internal application units 13A to 13C appropriately read out data from the electric power system DB 12, and transmit/receive messages including the data to/from each other.
In this manner, queuing is directly performed mainly between the internal application units 13A to 13C in the conventional electric power system. Thus, messages are transmitted/received according to a method unique to each of the internal application units 13A to 13C. Such a method is called an interconnection method.
Recently, queuing for a plurality of applications and queuing for an external application are becoming indispensable even in an internal application, along with developments in smart communities.
In message queuing between applications, messages are transmitted/received via a common bus 14 in a monitoring apparatus 10b and a plurality of bus connection adapters 15A to 15C, as shown in FIG. 2. Such a method is called a common bus method.
Each of the bus connection adapters 15A to 15C includes a messaging layer L1, connecting layer L2, and adapter layer L3. The messaging layer L1 has a message transmission/reception function. The connecting layer L2 has a function of connecting to the common bus 14. The adapter layer L3 has a message processing function and a queuing function for an existing system.
Also, in message queuing between the applications, the types of processing contents (to be also referred to as services hereinafter) are increasing, and the following CIS (Component Interface Specification) standards are defined.                IEC 61970-401: CIS (Component Interface Specification)—framework        IEC 61970-402: CIS—common service        IEC 61970-403: CIS—GDA (General-purpose Data Access)        IEC 61970-404: CIS—HSDA (High-Speed Data Access)        IEC 61970-405: CIS—GES (General-purpose Event and Subscription)        IEC 61970-407: CIS—TSDA (Time-Series Data Access)        
These standards are classified in accordance with services. For example, the HSDA service is high-priority processing, and message processing must be executed with priority over other services.
Examples of a priority control request are as follows.                Pass other messages                    Pass other messages by raising priority in accordance with a service.            Processing with particularly high urgency passes other messages even for the same service.            Pass other messages even for the same service if a delay occurs in processing due to, e.g., a network load.            Transmit a message even when an error occurs in a transmission process.                        
The priority control as described above can be implemented by, e.g., a dispatcher 20 which dispatches a message as shown in FIG. 3. As the dispatcher 20, a JMS (Java Messaging Service) server of Java™ or the like can be used.
In the interconnection method as described above, however, the internal application units 13A to 13C transmit/receive messages by their respective unique methods, and this makes message priority control difficult.
Also, in the common bus method, the dispatcher 20 performs priority control on a message flowing through the common bus 14 and arriving at the dispatcher 20. This makes it difficult to perform priority control on messages flowing through the common bus 14.
A problem to be solved by the present invention is to provide a message control program capable of implementing priority control of messages flowing through a common bus.